1. Field of the Invention
The present invention relates to a memory management system, a computer program thereof and a memory management method. The present invention particularly relates to a memory management system and a memory management method enabling establishing a highly reliable system.
2. Description of the Related Art
The capacity of an RAM (random-access memory which will be referred to as xe2x80x9cmemoryxe2x80x9d hereinafter) is very limited in a built-in equipment, and an application operating in the built-in equipment is, therefore, required to efficiently use the memory. Recently, there are cases where an application is downloaded from an external of the equipment through an external interface. In these cases, it is impossible to know in advance that the application thus downloaded operates stably in the equipment. A system executing and managing the application, therefore, desirably has a function to protect the system itself by some method.
Nevertheless, no measures have been taken for the conventional equipment, with the result that the entire system disadvantageously malfunctions due to the trouble of the application.
It is an object of the present invention to provide a novel memory management system and a management method therefor as well as a memory management system using the memory management method capable of limiting an application from illegally using a memory and protecting the system itself by registering a memory size to be used by the application dynamically using the memory in advance for the memory management system which is a system managing the dynamic memory, and by prohibiting the application from using the memory to exceed the registered memory size.
It is another object of the present invention to provide a computer program for managing the memory management system.
To attain the above-stated objects, the present invention basically adopts the following technical configurations.
The first aspect of the present invention is a memory management system for managing memory and for causing an application to execute using the memory, the memory management system comprising: a first means for registering an allocatable memory region for causing the application to execute on a memory management table provided for memory management; a second means for receiving an allocation request, in a case in which the application issues the allocation request for requesting to allocate a necessary memory size to the application, to the memory management system; a third means for determining whether or not the memory size requested by the allocation request is allocatable to the application; and a fourth means for registering the memory size and a region allocated for the memory size on the memory management table and notifying the application that the requested memory size has been allocated, if the memory size is allocatable based on determination of the third means, and for notifying the application that the requested memory size is non-allocatable, if the requested memory size is non-allocatable.
The second aspect of the present invention is a memory management system comprising a fifth means for receiving a second allocation request, in a case in which a second application that is different from the application issues the second allocation request for requesting to allocate a necessary memory size to the second application, to the memory management system; a sixth means for determining whether or not the memory size requested by the second allocation request is allocatable to the second application; and a seventh means for registering the memory size and a region allocated for the memory size on the memory management table and notifying the second application that the requested memory size has been allocated, if the memory size is allocatable based on determination of the sixth means, and for notifying the second application that the requested memory size is non-allocatable, if the requested memory size is non-allocatable.